Roundabout collision - who is at fault? With diagram

Red car only has priority if the left exit road has two lanes, if the left exit road is single lane then the red car should've been in the left lane when entering the roundabout. The diagram is somewhat confusing as it doesn't show the exits from the roundabout and their relation to the 12 o'clock rule, or how many lanes the roundabout exit roads have.

This is Wakefield isn’t it? Near Thornes Park. The blue car is at fault but it may go 50/50 annoyingly!

Blue however did red change lane from right to left whilst on the roundabout?

This is what I would say. Blue car is at fault, as it was in the wrong lane for where it intended to go. Red car was in the right lane for where it was heading.

Ha! There is certainly no age limit on stupid driving!
One of my personal bugbears is bad lane positioning on roundabouts, there is one near where I live where many drivers stick in the left hand land to use the 4th exit on a 5 exit roundabout.
The other issue I see really often is people indicating incorrectly or not at all.

Blue car’s fault. Blue indicated incorrectly, didn’t give way to Red car (priority to the right) and once it realised it wasn’t supposed to be going left, it should have either exited left anyway and found somewhere safe to turn and return to the roundabout, or signalled right to move into Red car’s lane if/when it was safe to do so.

If you were blue car, you should have given way to the right.

In a roundabout you give way to traffic coming from the right. Doesn't matter what it's doing. That's why roundabouts work. Red was on the roundabout blue should have waited for red to pass before pulling out. Blue is at fault

For me photos makes it very clear it’s blue cars fault. Hope you and bump are ok OP

Probably worth you double checking there are no road markings or signs on the little side road, as it would obviously help your case if it’s labelled as left lane for left turns only.

If blue was indicating then entirely at fault, as red car checking would understand this to mean their way was clear to exit.

Had an identical bump a few years ago. I was blue car and red bombed across roundabout and took us out. Red car tried to claim entire fault was with me. Both police and insurance said roundabout collisions are usually 50/50 unless witnesses/footage to show otherwise.

You were not in the wrong, the blue car manoeuvred badly around the roundabout as well as indicating incorrectly.
However one of the key skills to learn when driving is to presume nothing about other road users - everyday when driving you will experience people doing incorrect, unsafe and unexpected things. Safe drivers learn to drive defensively and not presume other road users will adhere to the rules.
I don’t wish to sound pompous (I know I do!) but that is one of the reasons older drivers have lower car insurance premiums we have learned to avoid other idiotic road users!
I hope you and your baby are OK, it must have been a dreadful experience.

Yes but the blue car, coming from a different direction, may not have been aware of that which is why they pulled out without realising the red car was going straight ahead. That's why I said it's likely a 50/50, neither is particularly at fault (red car is in the right for following road markings but blue is right for following the Highway Code).

Yes I drive and have had my license for over 20years and never had an accident, not sure what that has got to do with anything though

I’ve changed it to move to exit rather than move lanes.

OP may not have moved lanes - there are a lot of roundabouts where the exit has more than one lane

Just read your update re blue car indicating left. ie indicating to turn off. So definitely blue car at fault.
Hope you have a camera on your car OP

The blue car is at fault as the rules are give way to the right and you were travelling in correct lane. HOWEVER I had exactly this scenario with a lorry who pulled out exactly like this when I was on the roundabout (big roundabout). I assumed he was going left as he travelled a short distance in the left lane, however he then pulled straight into my path across the junction I was exiting at as he was going straight over. Technically he was in correct lane for going either left or straight over. But he shouldnt have cut across my path. Clipped my wing and damaged his bumper. Ended up in court as I refused to accept liability. Ended up going 70/30 in their favour. Judge decided I should have anticipated his manoeuvre and should have stopped. Bloody ridiculous. I SHOULD HAVE STOPPED SLAP BANG IN THE MIDDLE OF A BUSY ROUNDABOUT? To give way to a lorry when it wasn't their right of way? It's a joke

But you said the blue car was indicating left did you move to exit before or after you made this observation?

See I was always taught you take the left lane of going straight ahead

In this case the roundabout markings say you can use either lane for going straight ahead.

Yes, but you don't then drive straight into the side of someone.

Blue car pulled onto the roundabout when it wasn’t safe to do so.
However I’m guessing it will be 50/50 fault, which is unfair.